Experimental investigations on the tensile behaviour of granite after heating and water-cooling treatment

Abstract

Thermal shock on tensile behaviour of granite is highly important for understanding of fracturing mechanism in hot dry rock. The effects of heating and water-cooling treatment (HWCT) on tensile behaviour of granite were investigated in this work. The granite samples were first heated to different predetermined temperatures and then rapidly cooled by water. The Brazilian split tests were carried out on the HWCT samples, and the strain gauges were used to measure the evolution of tensile deformation. With the increasing of heating temperature, the tensile stress–strain curves change from linear to nonlinear, the axial tensile strain corresponding to failure point increases, and the tensile strength and tensile elastic modulus undergo a slight increase to decrease as the temperature increases. Finally, the mechanical properties under tensile condition were compared with those under compressive condition. Below 300 °C, the temperature has slight effect on both tensile and compressive strengths. Above 300 °C, the tensile properties decrease significantly after heating temperature threshold of 300 °C, while the heating temperature threshold for compressive properties is 500 °C. The thermal shock has a greater effect on tensile strength than on compressive strength.